Bicycle fork-crown and method of making same.



No. 650,964. F. C. BILL-I'NGS.

BICYCLE FORK CROWN AND METHOD-0F MAKING SAME.

Patented hme 5 1900.

(Application Bled June 8, 1898.)

(Ntr Model.)

Jag-I.

lnve ntar 1 a. Railings,

By 7264 Jiforney UNITED STATES PATENT OFFICE.

FREDERIC C. BILLINGS, OF HARTFORD, CONNECTICUT.

BICYCLE FORK-CROWN AND METHOD OF MAKING SAME.

SPECIFICATION forming part of Letters Patent No. 650,964, dated June 5, 1900.

v j Application filed June s, 18 3. Serial No. 682,889. on model.)

To all whom it may concern:

Be it known that I, FREDERIC O. BILLINGS,

a citizen of the United States, residin gin Hartford, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in the Art of Manufacturing Fork-Crowns for Bicycles or Velocipedes and in the Article so Produced, of which the following is a specification.

This invention relates to improvements in the art of manufacturing fork-crowns for bi cycles or velocipedes and to the article so produced and it has forits main object the production as a new article of manufacture of an improved hollow fork-crown formed from a single forging and having a homogeneous structure throughout of great density and substantially without defects at any point in the body or surface of the same.

Fork-crowns as heretofore constructed have casting, by pressing together stampings of sheet metal, or by welding together such stampings. The weakness and general undesirability of stam'pings of any type in the constructionof a high-grade bicycle are well understood, and castings of the fi hollow arched type are not as strong as they should be for the purpose. A wrought forged hollow forkcrown is theoretically the best type of this article that can be employed; but, so far as I am aware, no practicable method of producing one has heretofore been known in the art, one of the chief difiiculties encountered in the making of such a fork-crown being due to the fact that, so far as known, itis impracticable to produce a hollow blank of the proper shape for bending to the finished form without distorting the blank to such an extent as to open seams or-otherwise weaken the article by the severe tensile strains exerted at certain points in the length of the blank while the latter is undergoing the 'final shaping operation or operations. I have discovered, however, that a solid bar or ro d usually,of course,.of steelmay.be forged into a solid angular blank somewhat sim ilar in contour to that of the completed fork-crown to be made therefrom and that this angular blank during the forging operation will be so compressed throughout the entire surface thereof as to have a homogeneous compressed outer portion or skin of considerable thickness surrounding a central substantially-unvslightly and flattened to produce a finished article without distorting said blank to any considerable extent during this last operation of bending and shaping by reforging. Hence this process forms an essential feature of my present invention, as, so far as I am aware, it is the only method by which a hollow forged fork-crown of homogeneous and dense str'ucture throughout can be produced without in any way distorting or weakening the metal shell-at vital point-s thereof. this process Iam enabled to produce not only been formed in many different ways, as by As a result of an improved-.forlcrown as a complete and single article of manufacture, but also as a direct result of the employment of the first two steps of the process a fork-crown blank of a type heretofore unknown in the art-viz an angular hollow fork-crown blank in which the shell is a dense compressed metal homogeneous in structure throughout, and therefore having substantially the same strength at all points in the length thereof-.this blank having a pair of arms connected with each other and usually also having an intermediate head in which the openings in the arms communicate with each other, this head and the adjacent portions of the two arms of the blank being at this time substantially in the same positions, and therefore having approximately the same shape as they have when the fork-crown is completed by the subsequent operationof bending and flattening by reforging.

In the drawings accompanying and forming part of this specification, Figure 1 is a side elevation, partly broken away, of a bar or rod from which my improved fork-crown may I be formed." Fig. 2 is a side elevatiompartly broken away, of an angular solid fork-crown blank formed by reforgin g the straightblank shown in Fig. 1 and compressing the latter between suitable dies, usually by drop-forging, in a manner which is well understood. Fig. 3 is a central longitudinal section of a hollow fork-crown blank havinga dense compressed body or shell resulting from the removal of the central core or body portion of the solid fork-crown blank shown in Fig. 2. Fig. 4 is a sectional side elevation of a finished fork-crown formed by bending or partially flattening the hollow fork-crown shown in Fig. 3 during reforgingof thelatter. Fig. 5 is an end view of the linished fork-crown blank shown in Fig. 4.

Similar characters designate like parts in all the figures of the drawings.

In carrying my process into effect for produeing first my improved fork-crown blank and afterward my improved completed forkcrown I take a solid bar or red, usually of steel, this bar being preferably straight, as shown at r, Fig. 1, and then forge this straight bar between suitable dies into a solid angular fork-crown blank substantially of the type shown by b, Fig. 2. The bar 0 is of considerably greater diameter than the diameter of the arms of the solid fork-crown blankb and substantially of the same diameter as the head 3, which is shown in Fig. 2 between the two arms 4 4. of the angular blank. During the process of forging this solid angular blank from the straight bar the metal is not only condensed and compressed throughout the entire surface of the blank, as is usual in drop-forging operations; but at the points where the two arms 4 4 join the head 3 and the latter rises from such. arms all of these three members of the angular blank are c011- nected directly with one another, the head being formed by the upward displacement of a portion of the metal between and at the upper ends of the outer sides of the two arms. Hence the metal bar '2' is not seriously distorted, even at that part thereof where the head is subsequently struck up by a compression of the straight bar between the dies. Therefore both along the upper and the under sides of the solid angular blank the metal of the latter retains its original condition as regards texture or fiber, and the fibers of the wrought-metal rod '2' are not injuriously distorted dining this important step in the process, which results in the formation of an angular solid blank having a somewhat-thick skin 5, completelyinclosing an inner substantially-uncompressed core or body port-i011, which, as is well known, is seldom compressed to any such extent as the metal at the surface of a blank. It will be noticed that during this first step in the operation substantially the only change in the contour of the blank at the under side thereof is the formation of a simple bend 6. At the upper side of the blank, however, not only is the extreme upper central portion 7 flattened out considerably, but the upper sides of the arms 4 4 are thrown upward substantially in parallel lines,

as shown at 8 8, Fig. 2, forming similar obtuse angles with the upper side faces of the arms 4 4.

As it is essential in bicycle construction that the components thereof should have the least weight consistent with great strength, the central substantially-uncompressed core or body portion of the angular blankb should now be removed, and this may be done in the usual way by drilling. In this case the two arms 4 4 are drilled out to form a passage extending entirely through the angular blank from end to end thereof, as indicated at 9, Fig. Here, as will be seen, the two branches of this passage unite within the head 3, thus forming a continuous passage through the two arms 4 4 and the head 3 and leaving only the dense skin 5 of the arms 4 4 and that of the head 3 to form a hollow or tubular forkcrown blank having two hollow arm portions connected with each other and a hollow head portion connected with both of such hollow arms in such a manner that the metal at all points in the hollow blank retains substantially its maximum tensile strength and is a dense homogeneous forging throughout its entire length.

For the final step of transforming the angular blank into the finished fork-crown such blank is bent and. somewhat flattened by reforging between a pair of suitable dies to bring the blank to the finished state, as shown by the fork-crown illustrated at 0, Figs. 4 and 5. It will be noticed that during this reforging operation the positions of the upper portions of the two arms 4 4 are not materially changed with respect to the head 3, the upper sides of these arms being thrown slightly upward more nearly into a straight line, this being done in practice substantially simultaneously with the reshaping of the arms from a circular into a fiat 0r elliptical cross-sectional form. The resultant article is a finished arched fork-crown having two arms flattened or substantially elliptical in cross-section and homogeneous in structure throughout their entire lengths and condensed and compressed throughout and retaining substantially all of the tensile strength of the hollow blank shown in Fig. 3, owing to the fact that neither of the arms is bent to any considerable extent at any point in its length, the bend in each arm being on a curve of considerable radius, thus preventing distortion by an excessive strain at any single point in either arm.

Having described my invention, I clai1n- 1. An improvement in the art of making fork-crowns, which consists in, first, forging a substantially-straight solid metallic barinto an angular bar having a relatively-thick com pressed skin of homogeneous structure and a substantially-uncompressed core; second, removing the major portion of said core by drilling to form a channel through the blank;

and third, reforging and bending the hollow ward bored out from eachend and reforged blank to form a finished fork-crown. into an arched fork-crown with flattened arms.

2. As an article of manufacture a crossseetionally-fiattened, arched, hollova', forged, FREDERIC BILLINGS' 5 metallicfork-crown,compressedandof homo- Witnesses:

geneous structure throughout, and formed W. B, MARSH, from an angular, solid, forged blank aft-er- HENRY BISSELL. 

